Bug 22865 – __traits(compiles) affects inferrence of attributes

``` @safe unittest { foo(); } auto foo() { immutable(ubyte)[] data; enum bar = __traits(compiles, cast(ubyte[])data); } ``` Whether bar evaluates to true or false in this context I do not know. In either case, it shouldn't directly affect whether or not @safe is inferred.

patch --- diff --git a/src/dmd/expressionsem.d b/src/dmd/expressionsem.d index 6eda68880..0c060fd0d 100644 --- a/src/dmd/expressionsem.d +++ b/src/dmd/expressionsem.d @@ -7629,6 +7629,8 @@ private extern (C++) final class ExpressionSemanticVisitor : Visitor // Check for unsafe casts if (!sc.intypeof && + !(sc.flags & SCOPE.compile && sc.flags & SCOPE.ctfe) && !(sc.flags & SCOPE.debug_) && !isSafeCast(ex, t1b, tob) && (!sc.func && sc.stc & STC.safe || sc.func && sc.func.setUnsafe())) ---

The basic problem is that the function scope is used to evaluate the enum value while we are more in a static scope that can see static things in parent scopes. There is no system for this in the D frontend now. We can only known if something static is evaluated (SCOPE.ctfe) or also if we are in a traits compile (SCOPE.compile). That fix is consequently not good but it does not break the test suite. There is something very conceptual about semantics on if the cast should be allowed or not in "particular contexts".

@dkorpel created dlang/dmd pull request #14144 "Fix issue 22865 - __traits(compiles) affects inferrence of attributes" fixing this issue: - Fix issue 22865 - __traits(compiles) affects inferrence of attributes https://github.com/dlang/dmd/pull/14144

dlang/dmd pull request #14144 "Fix issue 22865 - __traits(compiles) affects inferrence of attributes" was merged into master: - 5314bf7194aff2dd4c08234472bfd0829db05e8c by Dennis Korpel: Fix issue 22865 - __traits(compiles) affects inferrence of attributes https://github.com/dlang/dmd/pull/14144